Method of reinforcing drill-pipes.



W. 0. MAXWELL AND H. SCHWAB.

METHOD OF REINFORCING DRILL PIPES.

APPLICATION FILED JULY 22, 19l8.

1,302,690. Patented May 6, 1919.

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UNITED sTATEs PATENT OFFICE.

WILLIAM o. MAXWELL, or Los ANGELES, AND nanny SCHWAB, or FELLOWS,CALIFORNIA; sun SCHWAB ASSIGNOR To SAID MAXWELL.

, METHOD OF BEINFORCING DRILL-PIPES.

Application filed July 22, Serial No. 246,160.

in Methods of Reinforcing Drill-Pipes, of-

which the followingis a specification.

Our principal object is to rebuild tubular drillstems, that is to takeworn. out drill stems and put them in condition for use, and ourinvention consists of the novel features herein shown, described andclaimed.

Figure 1 is a fragmentary perspective illustrating our method ofrebuildingtubular drill stems.

Fig. 2 is a sectional detail through the end of a drill stem and furtherillustrating the method.

Fig. 3 is a sectional detail of drill stem ready for use.

In the old oil fields there are large quantities of tubular drill stems.which have been discardedas' unfit for use. These old tubular drillstems have been weakened by rusting, the threads have become worn andbroken and the bodies ofthe stems are too weak and thin to stand newthreads, and it is the object of our invention to go into the oil fieldsand take these discarded drill stems and rebuildthem and put them in.condition for use. 1

These old drill stems are usually eighteen or twenty feet long and sixinches in diamthe rebuilt eter and weigh about twenty-five pounds to allthe foot. We take the old drillstem 1 and cut off the damaged ends hackof the 'ori "nal threads and back of the original I) acksmithed orup-set reinforcements to produce a clean finished end 2. The inside ofthis end 2 is thoroughly cleaned and smoothed up, for

a distance of-six or eight inches inlength by running 'a shell reamer ofthe proper size into the end and by dipping the endin; acid.

and by scrubbing with a wire brush; l-The particular: requirements mayfdiffer with each drill stem. {If the drill stem is smooth and unpittedon the 'inside,litsis. onlly necessary'to clean with ac d and;scrub,

Specification of Letters Patent.

-. borax, in throug ut usu allyithe old drill is not perfeetly -roundand-isinternally-pitted"with rilety findit-is' ,better to run i'ni ashellfreamer sofas to produce' ':perfectly round and fsmoothJS at:

Patented Ma o, 1919.

4 is a section of steel tubing or casing five andfive-eighths inches indiameter, having a six 1I1Cl1 drill stem and out six or eight incheslong. This reinforcement is cleaned on its outer face either by turningin a lathe or by dlpping in acid and scrubbing, and then thereinforcement is forced into the seat 3 reasonably tight until the outeredges are flush. 'After the reinforcement ring has been properly appliedthe drill stem is taken to a furnace 5, which may be heated with gas oroil, lifting tongs 6 are applied to the center of the stem and thelifting tongs are operated by a block and tackle 7 mounted to run upon atrack bar 8 so that the drill stem may be picked up bodily and the end 2placed in the furnace in position to be heated. A two-handled wrench 9is applied to the drill stem for rotating the drill stem. The furnace 5has a semicircular seat 10 to receive the: drill stem 1 and a verticallysliding door 11 with a seat 12 to match the seat 10. At the oppositeside of the furnace from the door 11 is a vertically sliding door 13.The two doors are closed until the fire is well started and the furnacehot, then the door 11 is raised, the tubular drill stem 1 manipulateduntil the end 2 passes inwardly through the seat 10 or beyond to thecenter of the furnace, and an operator manipulates the block and tackle7 and the wrench 9 to move the drill longitudinally in or out toproperly locate the end 2 and to raise the opposite end of the tubulardrill stem to a helght considerably above the end 2. Then after the end2 has been heated to about2000 F., another operator raises thedoor 13 tolace suitable flux, such as ii the reinforcing ring 4 to a point beyondthe inner end of the reinforcement, thenas the tubular drill stem isroitated the flux will run around in the trough at the inner end of thereinforcing ring and run into the seat 3 around-the reinforcing ring.This second operator uses a spoon Igor. tongs to insert spelter throughthe rei i-forcing ring 4 and the spelter'will melt to "form a puddle 14,in the trough at the innerend {of the reinforcing rin 4, and as thestem:1 is slowly rotated and t e temperature slightly increasedthe end ofthe stem ,.-v\rill enlargehyexpansion more than the reinforcement andthe; 's'pelter will run into the-seat 3 around the reinforcement and thewere m b ea ed en'fi l' e n w tor is satisfied. Usually the spelter willrun through the seat 3 until it may be seen at the end of the stem 1 inthe crack between the stem and the reinforcement. Then the stem isremoved from the furnace and cooled and in due course a new thread 15 isout upon the periphery of the stem, the reinforcing ring 4 serving tosupport the material during the thread cutting operation and to supportthe threads during the life of the tubular drill stem. The reinforcementis considerably longer than the thread 15 so that there is no liabilityof the thread breaking.

The spelter used is a composition of copper and tin tempered withphosphorus and this spelter will easily run or flow into the seat 3around the reinforcing ring 4 and a sufficient quantity should beapplied to form the spelter fillet 16 at the inner end of thereinforcement. At the time the spelter is flowing the outer shell of theend 2 is directly receiving the heat from the furnace and willbeconsiderably hotter than the reinforcing ring 4 and this difference inheat will cause the outer shell to expand enough to allow .the spelterto flow freely to the seat and then when the parts cool the outer shellwill turn up so that the outer shell, the spelter and the/inner shellare practically onebody,

By the use of our method it is perfectly practical to take an equipment,go out in an oil field, gather up the old discarded tubularidrill stemsand rebuild the drill stems and make them as good as new.

Many attempts have been made to rebuild tubular drill stems byblack-smithing and welding, up-set and the like, but it has proven afallure, because the material of the old tubular drill stem will notstand the black-smithing and welding. It is oxidized and hard andbrittle and deficient for the purpose of welding. The welding processrequires a great deal higher temperature and destroys the substance ofthe drill stem. In the brazing method as above described the structureof the drill stem is not disturbed or reformed and consequently it isnot injured or destroyed.

Various changes may be made without departing from the spirit of ourinvention, as claimed.

We claim:

1. The method of rebuilding tubular drill stems which consists incutting off the damaged end of the old stem end to form a new end,cleaning out the new end, inserting a reinforcing ring, placing the newend in a furnace with the opposite and elevated, placing flux in throughthe reinforcing ring to its inner end, placing spelter in through thereinforcing ring to its inner end, and continuing the application ofheat and rotating the stem so that the spelter and flux will flowbetween the reinforcing ring and the stem.

2. The method of rebuilding tubular drill stems which consists ofcutting off the damaged end to form a new end, cleaning the new end,inserting a reinforcing ring, hoisting the drill stem and placing thenew end in a furnace with the opposite end elevated, rotating andmanipulating the drill stem,

, applying heat, placing flux in through the reinforcing ring to itsinner end, placing spelter in through the reinforcing rin to its innerend, and continuing the app ication of heat and rotating the stem sothat the stem will expand until the flux and spelter flows between thereinforcing ring and the stem.

In testimony whereof we have signed our names to this specification.

I WILLIAM O. MAXWELL.

HENRY SCHWAB.

